(1) Field of the Invention
The present invention relates to a continuously advancing track surfacing machine for compacting a ballast bed supporting a track consisting of two rails fastened to ties, the rails having facing gage sides and the ties having opposite ends, which comprises a machine frame, front and rear undercarriages supporting the machine frame on the track for mobility in an operating direction, a drive for propelling the machine frame along the track, and a power actuated, vertically adjustable track stabilization assembly mounted on the machine frame between the undercarriages, the track stabilization assembly including rail-engaging roller tools, drive means for pressing the roller tools into engagement with the facing gage sides of the rails and means for vibrating the roller tools. The machine further comprises a drive for vertically adjusting the track stabilization assembly and a track leveling reference system monitoring the track level.
(2) Description of the Prior Art
Machines of this type for compacting and dynamically stabilizing a ballast bed are disclosed in U.S. Pat. Nos. 4,046,078 and 4,046,079, dated Sept. 6, 1977. Such track surfacing machines are either coupled to intermittently advancing track leveling, lining and tamping machines or are operated immediately therebehind to settle the tamped ballast bed by further compaction. In this way, the dynamic ballast stabilization anticipates the lower track level which would be attained under the loads of the trains passing over the tamped track and solidly embeds the track ties in the stabilized ballast whereby the resistance against any lateral track displacement is increased. The track stabilization assembly disclosed in these patents may be used in the present track surfacing machine and comprises a tool carrier frame supported on the track rails by flanged rollers which are spread apart into pressing engagement with the facing gage sides of the rails. Gripping rollers are mounted on the tool carrier frame and may be pivoted into clamping engagement with the rail heads at the field sides thereof whereby each rail is firmly engaged between the flanged rollers and the gripping rollers. The tool carrier frame is subjected to vibrations extending transversely to the track and to vertically downwardly extending loads. These forces cause the firmly gripped track to be driven into the ballast bed, imparting a flowing motion to the ballast stones which re-orients the ballast stones and moves them closer together. This enhances the compaction of the ballast under, and at the ends of, the previously tamped ties while it settles the track at a lower level because of the reduced ballast volume. This dynamic track stabilization has been used with great success in track maintenance and rehabilitation.
Canadian patent No. 1,191,739 discloses the use of such track stabilization machines in a train of sequentially arranged track maintenance machines whose work may be synchronized and which may comprise an intermittently advancing track leveling, lining and tamping machine as well as continuously advancing track stabilization and ballast cleaning machines.
U.S. Pat. No. 4,643,101, dated Feb. 17, 1987, discloses a continuously advancing track leveling, lining and tamping machine equipped with a track stabilization assembly. This is a special type of a combined track tamping and stabilizing machine which frequently requires the subsequent use of a ballast plow to deliver ballast into the cribs since a portion of the crib ballast has been moved out of the cribs under the adjacent ties during the preceding track tamping and stabilizing operation.
U.S. Pat. No. 4,064,807, dated Dec. 27, 1977, discloses a non-stop track leveling and ballast compacting machine comprising a track leveling reference system. The machine frame carries a track lifting device for raising successive track sections as the machine continuously advances along the track, a plow for smoothing the ballast bed below the raised track sections and a track stabilizing ballast compactor trailing the plow in the operating direction. The machine frame is supported by front and rear undercarriages on the track and the plow is arranged centrally between the undercarriages. The plow has plowshares arranged to form two elongated raised ballast strips below the track rails and an intermediate strip recessed between the two raised strips so that the track ties will not "ride" on their ballast support. This combination of a track stabilization assembly with a plow moving under preceding raised track sections provides a firm, smooth ballast bed for the track, in contrast to such track surfacing machines as disclosed in U.S. Pat. No. 3,651 587, dated Mar. 28, 1972, and U.S. Pat. No. 4,282,663, dated Aug. 11, 1981, which are ballast plows with plow arrangements which are lowered into engagement with the ballast bed for smoothing the surface of the ballast supporting the track.
British Pat. No. 1,006,639, published Oct. 6, 1965, discloses an apparatus for clearing ballast from the center of the ballast bed towards the two rails, which comprises two vertically adjustable rotary devices with radially projecting, flexible ballast sweeping elements, the rotary devices being rotatable about axes extending in the direction of the track for displacing ballast into the areas of the rails where the ballast may be tamped under the ties.